TechDocs "HOW TO" guides

How to migrate from TechDocs Basic to Recommended deployment approach?

The main difference between TechDocs Basic and Recommended deployment approach is where the docs are generated and stored. In Basic or the out-of-the-box setup, docs are generated and stored at the server running your Backstage instance. But the recommended setup is to generate docs on CI/CD and store the generated sites to an external storage (e.g. AWS S3 or GCS). TechDocs in your Backstage instance should turn into read-only mode. Read more details and the benefits in the TechDocs Architecture.

Here are the steps needed to switch from the Basic to Recommended setup -

1. Prepare a cloud storage

Choose a cloud storage provider like AWS, Google Cloud or Microsoft Azure. Follow the detailed instructions for using cloud storage in TechDocs.

2. Publish to storage from CI/CD

Start publishing your TechDocs sites from the CI/CD workflow of each repository containing the source markdown files. Read the detailed instructions for configuring CI/CD.

3. Switch TechDocs to read-only mode

In your Backstage instance's app-config.yaml, set techdocs.builder from 'local' to 'external'. By doing this, TechDocs will not try to generate docs. Look at TechDocs configuration for reference.

How to understand techdocs-ref annotation values

If TechDocs is configured to generate docs, it will first download source files based on the value of the backstage.io/techdocs-ref annotation defined in the Entity's catalog-info.yaml file. This is also called the Prepare step.

We strongly recommend that the backstage.io/techdocs-ref annotation in each documented catalog entity's catalog-info.yaml be set to dir:. in almost all situations. This is because TechDocs is aligned with the "docs like code" philosophy, whereby documentation should be authored and managed alongside the source code of the underlying software itself.

When you see dir:., you can translate it to mean:

That the documentation source code lives in the same location as the catalog-info.yaml file.
That, in particular, the mkdocs.yml file is a sibling of catalog-info.yaml (meaning, it is in the same directory)
And that all of the source content of the documentation would be available if one were to download the directory containing those two files (as well as all sub-directories).

The directory tree of the entity would look something like this:

├── catalog-info.yaml
├── mkdocs.yml
└── docs
    └── index.md

If, for example, you wanted to keep a lean root directory, you could place your mkdocs.yml file in a subdirectory and update the backstage.io/techdocs-ref annotation value accordingly, e.g. to dir:./sub-folder:

├── catalog-info.yaml
└── sub-folder
    ├── mkdocs.yml
    └── docs
        └── index.md

In rare situations where your TechDocs source content is managed and stored in a location completely separate from your catalog-info.yaml, you can instead specify a URL location reference, the exact value of which will vary based on the source code hosting provider. Notice that instead of the dir: prefix, the url: prefix is used instead. For example:

GitHub: url:https://githubhost.com/org/repo/tree/<branch_name>
GitLab: url:https://gitlabhost.com/org/repo/tree/<branch_name>
Bitbucket: url:https://bitbuckethost.com/project/repo/src/<branch_name>
Azure: url:https://azurehost.com/organization/project/_git/repository

Note, just as it's possible to specify a subdirectory with the dir: prefix, you can also provide a path to a non-root directory inside the repository which contains the mkdocs.yml file and docs/ directory.

e.g. url:https://github.com/backstage/backstage/tree/master/plugins/techdocs-backend/examples/documented-component

Why is URL Reader faster than a git clone?

URL Reader uses the source code hosting provider to download a zip or tarball of the repository. The archive does not have any git history attached to it. Also it is a compressed file. Hence the file size is significantly smaller than how much data git clone has to transfer.

How to customize the TechDocs home page?

TechDocs uses a composability pattern similar to the Search and Catalog plugins in Backstage. While a default table experience, similar to the one provided by the Catalog plugin, is made available for ease-of-use, it's possible for you to provide a completely custom experience, tailored to the needs of your organization. For example, TechDocs comes with an alternative grid based layout (<EntityListDocsGrid>).

This is done in your app package. By default, you might see something like this in your App.tsx:

const AppRoutes = () => {
  <FlatRoutes>
    <Route path="/docs" element={<TechDocsIndexPage />}>
      <DefaultTechDocsHome />
    </Route>
  </FlatRoutes>;
};

But you can replace <DefaultTechDocsHome /> with any React component, which will be rendered in its place. Most likely, you would want to create and maintain such a component in a new directory at packages/app/src/components/techdocs, and import and use it in App.tsx:

import { CustomTechDocsHome } from './components/techdocs/CustomTechDocsHome';
// ...
const AppRoutes = () => {
  <FlatRoutes>
    <Route path="/docs" element={<TechDocsIndexPage />}>
      <CustomTechDocsHome />
    </Route>
  </FlatRoutes>;
};

How to customize the TechDocs reader page?

Similar to how it is possible to customize the TechDocs Home, it is also possible to customize the TechDocs Reader Page. It is done in your app package. By default, you might see something like this in your App.tsx:

const AppRoutes = () => {
  <Route path="/docs/:namespace/:kind/:name/*" element={<TechDocsReaderPage />}>
    {techDocsPage}
  </Route>;
};

The techDocsPage is a default techdocs reader page which lives in packages/app/src/components/techdocs. It includes the following without you having to set anything up.

<Page themeId="documentation">
  <TechDocsReaderPageHeader />
  <TechDocsReaderPageSubheader />
  <TechDocsReaderPageContent />
</Page>

If you would like to compose your own techDocsPage, you can do so by replacing the children of TechDocsPage with something else. Maybe you are just interested in replacing the Header:

<Page themeId="documentation">
  <Header type="documentation" title="Custom Header" />
  <TechDocsReaderPageContent />
</Page>

Or maybe you want to disable the in-context search

<Page themeId="documentation">
  <Header type="documentation" title="Custom Header" />
  <TechDocsReaderPageContent withSearch={false} />
</Page>

Or maybe you want to replace the entire TechDocs Page.

<Page themeId="documentation">
  <Header type="documentation" title="Custom Header" />
  <Content data-testid="techdocs-content">
    <p>my own content</p>
  </Content>
</Page>

How to migrate from TechDocs Alpha to Beta

This guide only applies to the "recommended" TechDocs deployment method (where an external storage provider and external CI/CD is used). If you use the "basic" or "out-of-the-box" setup, you can stop here! No action needed.

For the purposes of this guide, TechDocs Beta version is defined as:

TechDocs Plugin: At least v0.11.0
TechDocs Backend Plugin: At least v0.10.0
TechDocs CLI: At least v0.7.0

The beta version of TechDocs made a breaking change to the way TechDocs content was accessed and stored, allowing pages to be accessed with case-insensitive entity triplet paths (e.g. /docs/namespace/kind/name whereas in prior versions, they could only be accessed at /docs/namespace/Kind/name). In order to enable this change, documentation has to be stored in an external storage provider using an object key whose entity triplet is lower-cased.

New installations of TechDocs since the beta version will work fine with no action, but for those who were running TechDocs prior to this version, a migration will need to be performed so that all existing content in your storage bucket matches this lower-case entity triplet expectation.

Ensure you have the right permissions on your storage provider: In order to migrate files in your storage provider, the techdocs-cli needs to be able to read/copy/rename/move/delete files. The exact instructions vary by storage provider, but check the using cloud storage page for details.
Run a non-destructive migration of files: Ensure you have the latest version of techdocs-cli installed. Then run the following command, using the details relevant for your provider / configuration. This will copy all files from, e.g. namespace/Kind/name/index.html to namespace/kind/name/index.html, without removing the original files.

techdocs-cli migrate --publisher-type <awsS3|googleGcs|azureBlobStorage> --storage-name <bucket/container name> --verbose

Deploy the updated versions of the TechDocs plugins: Once the migration above has been run, you can deploy the beta versions of the TechDocs backend and frontend plugins to your Backstage instance.
Verify that your TechDocs sites are still loading/accessible: Try accessing a TechDocs site using different entity-triplet case variants, e.g. /docs/namespace/KIND/name or /docs/namespace/kind/name. Your TechDocs site should load regardless of the URL path casing you use.
Clean up the old objects from storage: Once you've verified that your TechDocs site is accessible, you can clean up your storage bucket by re-running the migrate command on the TechDocs CLI, but with an additional removeOriginal flag passed:

techdocs-cli migrate --publisher-type <awsS3|googleGcs|azureBlobStorage> --storage-name <bucket/container name> --removeOriginal --verbose

Update your CI/CD pipelines to use the beta version of the TechDocs CLI: Finally, you can update all of your CI/CD pipelines to use at least v0.x.y of the TechDocs CLI, ensuring that all sites are published to the new, lower-cased entity triplet paths going forward.

If you encounter problems running this migration, please report the issue. You can temporarily revert to pre-beta storage expectations with a configuration change:

techdocs:
  legacyUseCaseSensitiveTripletPaths: true

How to implement your own TechDocs APIs

The TechDocs plugin provides implementations of two primary APIs by default: the TechDocsStorageApi, which is responsible for talking to TechDocs storage to fetch files to render, and TechDocsApi, which is responsible for talking to techdocs-backend.

There may be occasions where you need to implement these two APIs yourself, to customize them to your own needs. The purpose of this guide is to walk you through how to do that in two steps.

Implement the TechDocsStorageApi and TechDocsApi interfaces according to your needs.

export class TechDocsCustomStorageApi implements TechDocsStorageApi {
  // your implementation
}

export class TechDocsCustomApiClient implements TechDocsApi {
  // your implementation
}

Override the API refs techdocsStorageApiRef and techdocsApiRef with your new implemented APIs in the App.tsx using ApiFactories. Read more about App APIs.

const app = createApp({
  apis: [
    // TechDocsStorageApi
    createApiFactory({
      api: techdocsStorageApiRef,
      deps: { discoveryApi: discoveryApiRef, configApi: configApiRef },
      factory({ discoveryApi, configApi }) {
        return new TechDocsCustomStorageApi({ discoveryApi, configApi });
      },
    }),
    // TechDocsApi
    createApiFactory({
      api: techdocsApiRef,
      deps: { discoveryApi: discoveryApiRef },
      factory({ discoveryApi }) {
        return new TechDocsCustomApiClient({ discoveryApi });
      },
    }),
  ],
});

How to add the documentation setup to your software templates

Software Templates in Backstage is a tool that can help your users to create new components out of already configured templates. It comes with a set of default templates to use, but you can also add your own templates.

If you have your own templates set up, we highly recommend that you include the required setup for TechDocs in those templates. When creating a new component, your users will then get a TechDocs site up and running automatically, ready for them to start writing technical documentation.

The purpose of this how-to guide is to walk you through how to add the required configuration and some default markdown files to your new template. You can use the react-ssr-template as a reference when walking through the steps.

Prerequisites:

An existing software template including a template.yaml together with a skeleton folder including at least a catalog-info.yaml.

Update your component's entity description by adding the following lines to the catalog-info.yaml in your skeleton folder.

annotations:
  backstage.io/techdocs-ref: dir:.

The backstage.io/techdocs-ref annotation is used by TechDocs to download the documentation source files for generating an entity's TechDocs site.

Create an mkdocs.yml file in the root of your skeleton folder with the following content:

site_name: ${{values.component_id}}
site_description: ${{values.description}}

nav:
  - Introduction: index.md

plugins:
  - techdocs-core

Create a /docs folder in the skeleton folder with at least an index.md file in it.

The docs/index.md can for example have the following content:

# ${{ values.component_id }}

${{ values.description }}

## Getting started

Start writing your documentation by adding more markdown (.md) files to this
folder (/docs) or replace the content in this file.

Note: The values of site_name, component_id and site_description depends on how you have configured your template.yaml

Done! You now have support for TechDocs in your own software template!

how to enable iframes in TechDocs

Techdocs uses the DOMPurify to sanitizes HTML and prevents XSS attacks

It's possible to allow some iframes based on a list of allowed hosts. To do this, add the allowed hosts in the techdocs.sanitizer.allowedIframeHosts configuration of your app-config.yaml

E.g.

techdocs:
  sanitizer:
    allowedIframeHosts:
      - drive.google.com

This way, all iframes where the host of src attribute is in the sanitizer.allowedIframeHosts list will be displayed.

How to add Mermaid support in TechDocs

To add Mermaid support in Techdocs, you can use kroki that creates diagrams from Textual descriptions. It is a single rendering gateway for all popular diagrams-as-a-code tools. It supports an enormous number of diagram types.

Create and Publish docker image: Create the docker image from the following Dockerfile and publish it to DockerHub.

FROM python:3.8-alpine

RUN apk update && apk --no-cache add gcc musl-dev openjdk11-jdk curl graphviz ttf-dejavu fontconfig

RUN pip install --upgrade pip && pip install mkdocs-techdocs-core==1.0.1

RUN pip install mkdocs-kroki-plugin

ENTRYPOINT [ "mkdocs" ]

Create a repository in your DockerHub and run the below command in the same folder where your Dockerfile is present:

docker build . -t dockerHub_Username/repositoryName:tagName

Once the docker image is ready, push it to DockerHub.

Update app-config.yaml: So that when your app generates techdocs, it will pull your docker image from DockerHub.

techdocs:
  builder: 'local' # Alternatives - 'external'
  generator:
    runIn: 'docker' # Alternatives - 'local'
    dockerImage: dockerHub_Username/repositoryName:tagName
    pullImage: true
  publisher:
    type: 'local' # Alternatives - 'googleGcs' or 'awsS3'. Read documentation for using alternatives.

Add the kroki plugin in mkdocs.yml:

plugins:
  - techdocs-core
  - kroki

Note: you will very likely want to set a kroki ServerURL configuration in your mkdocs.yml as well. The default value is the publicly hosted kroki.io. If you have sensitive information in your organization's diagrams, you should set up a server of your own and use it instead. Check out mkdocs-kroki-plugin config for more plugin configuration details.

Add mermaid code into techdocs:

```kroki-mermaid
sequenceDiagram
GitLab->>Kroki: Request rendering
Kroki->>Mermaid: Request rendering
Mermaid-->>Kroki: Image
Kroki-->>GitLab: Image
```

Done! Now you have a support of the following diagrams along with mermaid:

PlantUML
BlockDiag
BPMN
ByteField
SeqDiag
ActDiag
NwDiag
PacketDiag
RackDiag
C4 with PlantUML
Ditaa
Erd
Excalidraw
GraphViz
Nomnoml
Pikchr
Svgbob
UMlet
Vega
Vega-Lite
WaveDrom

How to implement a hybrid build strategy

One limitation of the Recommended deployment is that the experience for users requires modifying their CI/CD process to publish their TechDocs. For some users, this may be unnecessary, and provides a barrier to entry for onboarding users to Backstage. However, a purely local TechDocs build restricts TechDocs creators to using the tooling provided in Backstage, as well as the plugins and features provided in the Backstage-included mkdocs installation.

To accommodate both of these use-cases, users can implement a custom Build Strategy with logic to encode which TechDocs should be built locally, and which will be built externally.

To achieve this hybrid build model:

In your Backstage instance's app-config.yaml, set techdocs.builder to 'local'. This ensures that Backstage will build docs for users who want the 'out-of-the-box' experience.
Configure external storage of TechDocs as normal for a production deployment. This allows Backstage to publish documentation to your storage, as well as allowing other users to publish documentation from their CI/CD pipelines.

Create a custom build strategy, that implements the DocsBuildStrategy interface, and which implements your custom logic for determining whether to build docs for a given entity. For example, to only build docs when an entity has the company.com/techdocs-builder annotation set to 'local':

export class AnnotationBasedBuildStrategy {
  private readonly config: Config;

  constructor(config: Config) {
    this.config = config;
  }

  async shouldBuild(_: Entity): Promise<boolean> {
    return (
      this.entity.metadata?.annotations?.['company.com/techdocs-builder'] ===
      'local'
    );
  }
}

Pass an instance of this Build Strategy as the docsBuildStrategy parameter of the TechDocs backend createRouter method.

Users should now be able to choose to have their documentation built and published by the TechDocs backend by adding the company.com/techdocs-builder annotation to their entity. If the value of this annotation is 'local', the TechDocs backend will build and publish the documentation for them. If the value of the company.com/techdocs-builder annotation is anything other than 'local', the user is responsible for publishing documentation to the appropriate location in the TechDocs external storage.

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